Vehicle instrumentation displays typically use air core gauges to display information to vehicle operators. A typical air core gauge incorporates two or more coils mounted in proximity to a rotational rotor. In response to current applied to the coils, the coils create a magnetic field having a resultant vector. The magnetic field acts on the magnetic rotor, which rotates to align itself with the magnetic field. A pointer attached to a spindle of the gauge rotates along with the rotor to indicate a measure of a parameter to the vehicle operator.
In designing air core gauge systems, it is desirable to attain quick response of the gauge and minimization of the effect of forces resistant to the gauge rotation, such forces include viscous friction, shear forces of the silicon damping fluid, friction between the spindle and bobbin bearing, moment of inertia of the pointer and imbalance of the pointer. To minimize the effects of the resistant forces, power applied to the gauge is at a high enough level where these forces are minimal compared to the magnetic forces produced by the coils. This high level of power applied to the gauge is power that would be otherwise available to the vehicle. The high level of power applied to the gauge also causes heating the gauge due to power dissipation in the coils and requires heat sinking of the electronic devices used to drive the gauges due to their increased power handling requirements.